we're just getting word that those letters laced with poison sent to president obama and senator roger wicker was indeed ricin. authorities are now saying it was a low grade, not necessarily but denies. in other words, it would not be fatal. it doesn't mean that it is any less dangerous. is potentially for those who come into direct contact with the. but the authorities are now saying it was a low great variety, still a threat. it would get the latest from peter barnes on that in just a second. in the meantime, this weapon in boston, as you know, they're looking at two potential suspects. but what is not suspect right now is the type of weapon used. crude but effective. one, the former marine lieutenant colonel says it could become the weapon of choice for terrorists in this country, whether they are terrorists from this country are not. explain what you mean by that and whether they have, in fact, come to our sure. >> well, the term ieds is relatively new, but the whole concept of what -- we use the term booby trap, really the same thing we have with ieds. certainly timothy mcveigh, t